During the late 1970s and early 1980s, many people sought to be able to fly affordably. As a result, many aviation authorities set up definitions of lightweight, slow-flying aeroplanes that could be subject to minimum regulation. The resulting aeroplanes are commonly called "ultralight" or "microlight", although the weight and speed limits are rarely the same between any two countries.

There is also an allowance of another 10% on Maximum Take Off Weight for seaplanes and amphibians, and some countries (such as Germany and France) also allow another 5% for installation of a ballistic parachute.

The safety regulations used to approve microlights vary between countries, the most strict being the United Kingdom and Germany, while they are almost non-existent in France and the United States. The disparity between regulations is a major barrier to international trade and overflight, as is the fact that these regulations are invariably sub-ICAO, which means that they are not internationally recognised.

In most affluent countries, microlights or ultralights now account for about 20% of the civil aircraft fleet.